Some of tubulointerstitial changes are frequently found in glomerular disorders. A wide range of interstitial lesions have also been observed in patients with IgA nephropathy. Percutaneous biopsy specimens taken from 74 kidneys of IgA nephropathy patients have been analysed. Obtained tissues were examined by LM, If and EM. Light microscopy, immunofluorescence and electron microscopy Morphologic changes have been classified into 5 groups according to WHO classification. Interstitial changes, cellular infiltrations, fibrosis and other lesions from all renal tissues have been analysed and according to their intensity semiquantitatively graded into 4 groups. Histopathologic analysis has most frequently revealed interstitial fibrosis and less frequently mononuclear cellular infiltration particularly in patients with more prominent glomerular changes. Therefore, we have as well as other authors, confirmed that interstitial changes represent an important prognostic factor in the IgA nephropathy development. However, analysis of repeated biopsy specimens to confirm this hypothesis is necessary.